Electric-tube lighting.



No. 702,314. Patented June [0, I902.

D. MGF. MOORE. ELECTRIC TUBE LIGHTING.

(Application filed Dec. 18, 1901.)

(No Motfel.)

,Q.;t "2 31117271102 (97m B 53:011121 u ai'imz Quack A l 5K @3744 UiT SITES PATNT @Fmose DANIEL MOFARLAN MOORE, OF NEWARK, NEV JERSEY.

ELECTRIC-TUBE LIGHTING.

, 1 SPECIFICATION forming part of Letters Iatent N 0. 702,314, dated June 10, 1902.

Application filed December 18,1901. f Serial No. 86,357. (No model.)

To all whom it ntcty concern.-

Be it known that I, DANIEL .;MoFARLAN MORE,a citizenof the United States, and a resident of Newark, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Electric Tube Lighting, of which the following is a specification.

My invention relates to those systems of electric lighting wherein the light is produced by electrically agitatinga column'of rarefied vided with energy-transferring terminals,

which by preference are in the form of metallic conducting-surfaces applied to the ends of the tubes in the form of caps or envelops.

The main purpose of the present invention is to secure greater economy or rather efficiency in the system already described by obtaining from the lamp a greater degree of illumination for a given expenditure of electric energy. 7

My present invention may briefly be stated to be the discovery that by increasing the length of the luminous column, or, in other words, the length of the path through the gaseous body from one terminal to the other of the lamp, the efficiency thereof may be greatly increased, or, in other words, in the discovery that by lengthening out the luminous column the expenditure of Watts per candle is reduced. r

The true end of my present invention may be best understood by taking a specific 'instance from the practice followed by me previously to my present invention as a standard of comparison. Given a tube or glass of from seven to eight feet in length and of, say, one and three-fourths inches in diameter, which is approximately the length of tube that can be readily produced and handled commercially,

it will befound that in order to produce the desired density of illumination in the contained gas or vapor an area of electric terminals orcaps upon the ends of the tube must be used which will practically amount to forty per cent. of the total length of tube Such a tube or lamp while it maybe made to produce a light of commercial density and even of high intensity. if the area of the caps be sufficient will befound to be not highly efficient, because the total exposed or illuminating'portion of the contained gas which is not covered by the opaque caps or terminals is small as compared with the total length of the gas containing tube or gas column. Hence the watts per candle of observed or illuminating area is necessarily high. It is not practicable, however, to greatly reduce the area of the caps or terminals withthe purpose of increasing the illuminating area of the tube as compared with the area of the caps, because it then becomes necessary to use a high voltage in order to get the required density. It is obvious, further, that the production of the required density or a commercial density and the attempt to secure efficiency by using high voltages is necessarily objectionable in practice, because of the risk of damage to persons and property incident to the use of high-tension electric currents on Wires used to distribute the energy from the point where the source of high potential is located to the point where the tube is mounted.

My present invention or discovery may be brieliy'stated to consist in this, to wit: that by lengthening out the illuminating gaseous column, (the area of the caps or terminals being kept such as to supply the proper amount of energy,) or, in other words, by usingadischarge-colun1n of high' resistance tlieelficiency will be greatly increased. Thus, for instance, to take a practical case, I have found that if with a light column of, say, eighteen inches available for illumination the watts per candle of total illumination should be, with a given voltage and a given area of terminalor double the watts per candle of total illumination would be only eleven, and another doubling ot the length of column would produce the volts will n ed to be increased 1.6 times,

or the cap area can be increased.

It is assumed in the foregoing that the area or the terminals is in each case the saute; but

even then the density per square inch of illuinitiating area would be only slightly lessened. Of course by increasing the area of the cap or terminal the density may be in-' creased in each instance of increase in the length oftuhe, so asto enable said caps to supply the necessary amount. of energy to produce the required density of light, and the density may be thus maintained or maybe even greater; Iuasm uch, however, as the pro-- portion of available illuminating column to the total gaseous col it ill n (which would include t hat covered by the caps) would be greatlyincreased by lengthening the tube, as described, it would be pertnissible to greatly increase the size of the cap and to thus maintain the density of the illumination; but with such increased area of cap and with a correspondingly greater transfer of energy to the tube to maintain or produce the required density thegeneral rule above stated would still hold trueto wit, that the watts per candle of effective illutnination would be decreased by lengthening the light-column. In fact, Ihave discovered that in a tube-lamp wherein the energy is supplied to a luminous column of gas through the electrostatic action of conducting caps or terminals upon the exterior of the tube of glass at the terminals of the column to be rendered luminous the major portion of energy is consumed in the transfer to and from the column at said caps. In other words, the total resistance of the lamp can be divided into two parts-first, the resistance at the two terminals of the glass column through which the electric energy passes, and, second, the resistance of the column itself; but the latter element of resistance is, as I have discovered, very low, and the gaseous column is, in fact, a verygood conductor and forms but a small proportion of the total resistance. As will be obvious, therefore, with a short tube a larger proportion of the total energy is consumed in the transfer to and from the column and-a much smaller proportion in the actual light-giving column; but by lengthening out the gaseous column the proportionate useful expenditure of energy in the lamp becomes verymuch greater. Thisconstitutesadistinct departure from previous practice, which has proceeded upon the assumption that the major portion of the consumption of energy took place in' the gaseous column and that hence it was not desirable to lengthen said column, whereas, as I have discovered, a greater resistance and consumption of energy takes place at the electrodes or terminals when made of proper size to produce the required density of light in the gas.

For example, if a given illumination in a room emanates from twenty-five tubes the electricity is transferred to and from the gas at fifty places, while if one long tube is used it is transferred only at two places. In other Words, my invention or discovery may be said to consist in using a gaseous filament or discharge-column for the type of lamp above described of high resistance, and by high resistance I mean high as compared with the lengthof column used by me previously to the present invention, where the density of practicable amount had been maintained by a cap area of the necessary surface.

Many useful results follow from the utilization of the above invention or discovery. First, it becomes possible to produce a luminous column of very great density and with a good efficieucy, because the increased cap area which is necessary to produce such a density bears but a small proportion to the length of the luminous column or column available for illumination. Secondly, and as a corollary of the above, it becomes possible to get a commercially-useful density with a very great length of column Without using a high degree of voltage. This results in the possibility of distributing the luminous or translucent tube over large areas and confining the cond ucting terminals or caps'to one location in a box or receptacle, which may be sealed and constructed with reference to securing immunity from danger byfire. In other words, it becomes possible to light a room or building by usinga continuous translucent tube distributed through the building in the desired locations and to render the same luminous by the attachment at its ends outside of the interior of the building of caps or terminals of proper area to supply the proper amount of electric energy.

Inasmuch as by increasing the size of the cap or terminal a correspondingly-greater amount of energy may be transferred to the gaseous contents, it becomes possible by my invention to produce the light commercially from commercial alternating circuits directly. There are many other advantages which follow from the use of my present invention, but which it is not necessary here to state.

In the accompanying drawings, Figure 1 shows a tube of proportions used by me prior able for illumination is contained in the narrow space unsheathed and making up approximately three-fifths of the total length of the tube. Inv Fig. 2 a tube is shown whose total length is approximately twelve times that of the former; but its light-column using approximately the same lengths or an even somewhat larger cap is approximately twenty times that of the first. In the tube shown in Fig. 2 an additional advantage is that the light will be more greatly diifused, but the actual efficiency or the return of total illumination for the watts consumed Will be very greatly increased, and by increasing the length of the caps the density may be brought up to that required, but with the same rule still holding goodthat the total illumination perwatts will be very greatly increased.

It will be obvious that myinvention is not limited to the use of straight tubes or to tubes curved, as shown in Fig. 3, but maybe extended to tubes coiled upon themselves, as indicated in Fig. 4, wherein the tube has caps or terminals which are still very short as compared with the whole length of the translucent tube, and where, therefore, it becomes possible to secure the required density with a low consumption of energy per candle, because the caps may be given such length as is required to transfer the proper amount of energy to the gaseous contents without obscuringthe gaseous column to a prohibitory extent.

It should be understood that, other things being equal,the'lengthening of the tube would resultin a slight decrease of the density of the light, but that even with such decreased density the total illumination per watt of applied energy is largely increased; but with the increased length the increase of the size of the cap to bringthe density up to the required amount becomes possible, and the efficiency per watt of applied energy as measured by the total illuminating area or length of exposed light-column is very much greater. It shouldbe understood, further, that an increase in the cross-section of the illuminating-tubes, other things being equal, would naturally result in decreasing the density, but that with an increased length, as above described, it becomes further possible to use tubes of larger diameter and to produce a practical or commercial density of light, and hence a larger diffusion, than would be possible with high density, or, on the other hand, it becomes possible to use tubes of great length and small cross-section and to give a high density per unit of illuminating area,[in which case the tube may be coiled, twisted, or given a zigzag form to bring all its illuminating capacity within a small area to give a light somewhat concentrated and less diffused than would be the case with a tube arranged to encircle or inclose the area to beilluminated or otherwise spread'out over such area.

What I claim "as my invention is 1. In an electric-lighting system wherein the light is produced by electrical agitation described, comprising a glass tube containing a rarefied gas or vapor and having opaque conducting sleeves, caps or terminals through which electricenergy is supplied by electrostatic action to the contents of the tube at the terminals or ends thereof, the translucent portion of said tube between terminals being elongated or extended longitudinally as described to give a great length of luminous column with relation to the length of cap or terminal, as and for the purpose set forth.

4:. In an electric lamp containing'a rarefied gas or vapor to be rendered luminous by elec-' tric energy supplied at the terminals of the gas-column, a glass tube provided with conducting terminals or caps appliedto'the exterior thereof, said tube being extended as described longitudinally to give a great length of light-giving tube as compared to the length of cap or terminal, as and for the purpose set forth.

5. In an electric-lighting system wherein the light is produced bythe electricalagitation of a rarefied gas or vapor contained ina translucent receptacle, a tube lamp having a gaseous column of great length included between the conducting caps or terminals which supply energy to the contents of the tube, substantially as and for the purpose described.

6. An electric lamp consisting of an allglass tube containing a rarefied gas or vapor and having conducting sleeves, caps or terminals through which the electric energy is supplied by electrostatic action to the contents of the tube, said tube being elongated as described to increase the length of the luminous column with relation to the length of obscuring-caps so as to secure a more useful expenditure of energy in overcoming the total resistance of the lamp, as and for the purpose described.

Signed at New York city, in the county of New York and State of New York, this 16th day of December, A. D. 1901.

DANIEL MCFARLAN MOORE.

\Vit-nesses:

E. L. LAWLER, II. C. TOWNSEND. 

